Even though typing them out may make them stupid but here are a few examples thinking out loud. Remember the body language is quite important and as you do more you start feeling more comfortable in your skin.

- Waiting for an elevator that never comes with two strangers. What I may say: I guess we'd be camping here tonight. Do you have your tent with you?

- Embarrassing moment: I hit my head lightly to something in front of 5 people: Act funny saying Oh can someone call an ambulance.

- Someone dropping yogurt from their spoon on their shirt and locking eye to eye with me realising I've been watching the moment: I would have an empathetic look and then act with an imaginary spoon picking from my own shirt and eating it.

Basically the kind of mild jokes/acts you would do and say to close people would work on strangers as well